Basic and Diluted Earnings Per Share Proforma Earnings per Share and Common Shares Outstanding due to stock split (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations (in dollars per share)	$ 1.29	$ 1.40
Discontinued Operations, Net of Tax (in dollars per share)	$ 0.17	$ 0.08
Earnings Per Share, Basic	$ 1.46	$ 1.48
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations (in dollars per share)	$ 1.28	$ 1.39
Discontinued Operations, Net of Tax (in dollars per share)	$ 0.17	$ 0.08
Net Income (in dollars per share)	$ 1.45	$ 1.47
Weighted Average Number of Shares Outstanding, Basic	179	177
Weighted Average Number of Shares Outstanding, Diluted	181	180
As Reported [Member]
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations (in dollars per share)	$ 1.29	$ 1.40
Discontinued Operations, Net of Tax (in dollars per share)	$ 0.17	$ 0.08
Earnings Per Share, Basic	$ 1.46	$ 1.48
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations (in dollars per share)	$ 1.28	$ 1.39
Discontinued Operations, Net of Tax (in dollars per share)	$ 0.17	$ 0.08
Net Income (in dollars per share)	$ 1.45	$ 1.47
Weighted Average Number of Shares Outstanding, Basic	179	177
Weighted Average Number of Shares Outstanding, Diluted	181	180
Pro Forma [Member]
Earnings Per Share, Basic [Abstract]
Income from Continuing Operations (in dollars per share)	$ 0.65	$ 0.70
Discontinued Operations, Net of Tax (in dollars per share)	$ 0.08	$ 0.04
Earnings Per Share, Basic	$ 0.73	$ 0.74
Earnings Per Share, Diluted [Abstract]
Income from Continuing Operations (in dollars per share)	$ 0.64	$ 0.69
Discontinued Operations, Net of Tax (in dollars per share)	$ 0.08	$ 0.04
Net Income (in dollars per share)	$ 0.72	$ 0.73
Weighted Average Number of Shares Outstanding, Basic	358	355
Weighted Average Number of Shares Outstanding, Diluted	362	359